U.S. patent number 4,211,574 [Application Number 05/819,080] was granted by the patent office on 1980-07-08 for process for making a solid impregnated precursor of a solution of cellulose.
This patent grant is currently assigned to Akzona Incorporated. Invention is credited to Clarence C. McCorsley, III, Julianna K. Varga.
United States Patent |
4,211,574 |
McCorsley, III , et
al. |
July 8, 1980 |
Process for making a solid impregnated precursor of a solution of
cellulose
Abstract
A process is provided for making a solid precursor of a solution
of cellulose in a tertiary amine oxide by suspending cellulose in a
mixture containing a tertiary amine oxide and water under
conditions where the amine oxide will not dissolve the cellulose
until sufficient amine oxide has been absorbed to dissolve the
cellulose when it is heated. An organic liquid which is not
chemically reactive with the amine oxide or cellulose but is
miscible with the tertiary amine oxide and is a non-solvent for the
cellulose may be included in the amine oxide-water mixture to
assist in the removal of excess water from the precursor or promote
better distribution of the tertiary amine oxide through the
cellulose.
Inventors: |
McCorsley, III; Clarence C.
(Asheville, NC), Varga; Julianna K. (Asheville, NC) |
Assignee: |
Akzona Incorporated (Asheville,
NC)
|
Family
ID: |
25227151 |
Appl.
No.: |
05/819,080 |
Filed: |
July 26, 1977 |
Current U.S.
Class: |
106/200.3 |
Current CPC
Class: |
C08L
1/00 (20130101); C08J 3/096 (20130101); C08L
1/00 (20130101); C08L 2666/02 (20130101); C08J
2301/02 (20130101) |
Current International
Class: |
C08L
1/00 (20060101); C08J 3/09 (20060101); C08J
3/02 (20060101); C08L 001/02 () |
Field of
Search: |
;106/186,198,125,163
;8/189 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Morris; Theodore
Attorney, Agent or Firm: Young; Francis W. Hall; Jack H.
Upchurch; Clelle W.
Claims
What is claimed is:
1. A process for making a precursor of a solution containing
cellulose dissolved in a tertiary amine oxide solvent for cellulose
which comprises impregnating cellulose with a liquid tertiary amine
oxide solvent containing water in an amount whereby the cellulose
does not dissolve in the solvent under the conditions of
impregnation but the cellulose becomes impregnated with the solvent
in an amount which will dissolve the cellulose after water is
removed and the impregnated cellulose is heated in the absence of
additional solvent.
2. The process of claim 1 wherein the said product is comminuted to
form cellulose chips adapted to be fed to an extruder.
3. The process of claim 1 wherein the amine oxide is
N-methylmorpholine oxide.
4. The process of claim 1 wherein the product contains from about
50% to about 90% by weight tertiary amine oxide, from 0 to 20
percent by weight water and from about 10% to about 40% by weight
cellulose.
5. The process of claim 1 wherein the cellulose is suspended in the
mixture at a temperature of from about 85.degree. C. to about
110.degree. C.
6. A process for making a precursor of a solution of cellulose in a
tertiary amine oxide which comprises suspending cellulose in a
mixture containing a tertiary amine oxide, water and an organic
liquid which is nonreactive chemically but is miscible with the
tertiary amine oxide and water and is a nonsolvent for cellulose
until liquid is absorbed by the cellulose, said mixture being a
nonsolvent for the cellulose at the temperature at which the
cellulose is suspended therein, and thereafter removing the
nonsolvent to provide a solid cellulose product containing absorbed
tertiary amine oxide and water which upon heating becomes a
solution of cellulose.
7. The process of claim 6 wherein the said non-solvent and water
are removed until the product consists of cellulose and absorbed
tertiary amine oxide containing water.
8. The process of claim 7 wherein the said product is comminuted to
form cellulose chips adapted to be fed to an extruder.
9. The process of claim 6 wherein the tertiary amine oxide is
N-methylmorpholine oxide.
10. The process of claim 6 wherein the product contains from about
50% to about 90% by weight tertiary amine oxide, from 0 to 20
percent by weight water and from about 10% to about 40% by weight
cellulose.
11. The process of claim 6 wherein the non-solvent and water are
removed until the cellulose tertiary amine oxide product contains
from about 0 to about 20 percent weight water.
12. The process of claim 6 wherein the cellulose is suspended in
the mixture at a temperature of from about 50.degree. C. to about
140.degree. C. and the non-solvent is removed under vacuum at a
temperature of from about 40.degree. C. to about 90.degree. C.
13. The process of claim 6 wherein the ratio of said mixture to
cellulose when mixed with the cellulose is from about 0.25 to about
2.5 parts by weight mixture per part by weight cellulose and the
ratio of tertiary amine oxide and water to the cellulose is from
about 1.5 to about 9 parts tertiary amine oxide and water per part
by weight cellulose after the said non-solvent is removed.
14. In a process for shaping a solution containing cellulose
dissolved in a solvent containing a tertiary amine oxide and water
and precipitating the cellulose to form a shaped solid cellulose
article, the improvement which comprises impregnating cellulose
with a liquid mixture which contains a tertiary amine oxide and
water which mixture is a nonsolvent for cellulose under the
conditions of the impregnation but the solvent is absorbed by the
cellulose, retaining the cellulose and absorbed solvent without the
cellulose dissolving until a solution is to be prepared, removing
water from the said nonsolvent to convert it into a solvent for
cellulose and heating the cellulose with absorbed solvent until the
cellulose dissolves in the solvent, shaping the solution, and
precipitating the cellulose from the shaped solution.
15. A solid precursor of a solution of cellulose in a tertiary
amine oxide comprising cellulose and absorbed tertiary amine
oxide.
16. The product of claim 15 containing 10 to 40% by weight solid
cellulose and about 50% to about 90% by weight of tertiary amine
oxide and water.
17. A process for making a precursor of a solution containing
cellulose dissolved in a tertiary amine oxide which comprises
mixing cellulose with a liquid mixture containing a tertiary amine
N-oxide solvent for cellulose and water which mixture is a
nonsolvent for cellulose,
maintaining the resulting mixture until the cellulose absorbs said
nonsolvent in an amount to provide sufficient tertiary amine oxide
to dissolve the cellulose after water is removed to convert the
said nonsolvent into a solvent for the cellulose.
18. In a process for making a cellulose fiber wherein a solution of
cellulose in a solvent therefor is spun to form a filament and the
cellulose in the filament is separated from the solvent to form a
cellulose fiber, the improvement which comprises preparing a solid
cellulose product which can be converted alone into a spinnable
cellulose solution, said improvement comprising the step of (1)
suspending cellulose in a tertiary amine oxide and water at a
temperature at which the cellulose will not dissolve in the amine
oxide, (2) maintaining the suspension until amine oxide and water
are absorbed by the cellulose in an amount capable of dissolving
the cellulose at a temperature above the temperature of the
suspension and (3) separating the cellulose having the amine oxide
absorbed therein from unabsorbed amine oxide and water to provide a
solid cellulose product which can be heated without the addition of
solvent to form a spinnable solution.
19. A comminuted cellulose product adapted to be converted into a
solution containing cellulose dissolved in a tertiary amine oxide
and water, said product comprising cellulose impregnated with a
solvent containing a tertiary amine oxide and water in an amount
which will dissolve the cellulose when the product is heated to
form a spinnable or extrudable solution without additional solvent
for the cellulose.
Description
This invention relates generally to regenerated cellulose and more
particularly to a process for preparing a solid cellulosicamine
oxide material which can be used for making cellulosic fibers and
filaments.
A process for dissolving cellulose in a tertiary amine oxide is
disclosed in U.S. Pat. No. 2,179,181. In accordance with the
disclosed process from 7 to 10% by weight of cellulose is dissolved
in 93 to 90% by weight of a tertiary amine oxide to form a viscous
liquid from which the cellulose may be precipitated by pouring the
liquid in water, alcohol or dilute acid. The tertiary amine oxides
suitable for practicing the disclosed process contain fourteen or
less carbon atoms and may be an oxide of a trialkyl amine or of an
alkylcycloaliphatic tertiary amine. The resulting solution has the
disadvantage of having a low solids content and a high
viscosity.
Another process for dissolving cellulose in a tertiary amine oxide
is disclosed in U.S. Pat. No. 3,447,939. A cyclic mono
(N-methylamine-N-oxide) such as N-methylmorpholine-N-oxide is used
as the solvent. The resulting solutions have much the same
disadvantages of those prepared by the process disclosed in U.S.
Pat. No. 2,179,181 because they are also of low solids content and
have a high viscosity.
In accordance with the process disclosed in U.S. Pat. No.
3,508,941, two or more different polymers are dissolved in a cyclic
mono (N-methylamine-N-oxide) compound and are precipitated together
to produce a random copolymer. A diluent such as dimethyl
sulfoxide, N-methyl-pyrrolidone or sulfolane may be added to the
solution to reduce its viscosity. As indicated by the examples set
forth in the patent, only low solids solutions can be prepared when
cellulose is one of the compounds used in the preparation of the
solution.
It is an object of this invention to provide a process for making a
solid product which is adapted to be heated to prepare a solution
of cellulose in a tertiary amine oxide. Another object of the
invention is to provide a chip or similar granular cellulosic
product which can be heated alone to form a solution of cellulose
in an amine oxide which is suitable for shaping and coagulating the
cellulose. Another object of the invention is to provide a process
for making a mixture of cellulose and amine oxide which can be
comminuted, stored and otherwise treated as a solid material and
can be heated later to convert the mixture into a solution of
cellulose in a tertiary amine oxide which is adapted for extrusion
or spinning. A more specific object of the invention is to provide
a cellulosic product which can be converted into a solution of
cellulose in a tertiary amine oxide which has a higher solids
content than the amine oxide solutions of the above discussed prior
art. A still more specific object of the invention is to provide a
precursor of a solution of cellulose in amine oxide which is a
solid at ambient temperatures but becomes a solution adapted to be
extruded or spun when heated to a temperature above ambient.
The foregoing objects and others are accomplished in accordance
with this invention, generally speaking, by providing a process
wherein cellulose is mixed with a liquid amine oxide in such
proportions and under conditions of temperature and pressure where
no substantial dissolution of the cellulose in the amine oxide will
occur, and the resulting mixture is steeped at such a temperature
until the cellulose absorbs amine oxide and water without
significant dissolution, and the excess water, if any, is stripped
from the saturated cellulose at a temperature which is also below
one at which significant dissolution of the cellulose in the amine
oxide occurs.
In one embodiment of the invention, cellulose is mixed with a
liquid solution of a tertiary amine oxide-water and liquid organic
non-solvent for cellulose in such proportions and at a temperature
below that where there will be any substantial dissolution of the
cellulose in the solution, and the resulting suspension is steeped
at such a temperature until the cellulose absorbs tertiary amine
oxide-water-non-solvent solution without significant dissolution,
and the non-solvent is removed from the mixture at a temperature
which is also below one at which significant dissolution of the
cellulose in the amine oxide occurs. Some of the water may be
removed with the non-solvent. In the embodiment where excess water
instead of an organic non-solvent is used to decrease the
solubility of the cellulose in the amine oxide, the excess water is
stripped from the cellulose after sufficient amine oxide has been
absorbed by the cellulose for subsequent complete dissolution. The
resulting solid product may be comminuted such as by grinding or
chopping to form fragments or chips which are suitable for
extrusion, spinning, molding or the like. They may be stored for
later conversion into a solution or they may be heated immediately
to form a solution and shaped.
The invention thus contemplates a process for making a solid
precursor of a solution of cellulose in a tertiary amine oxide
which involves suspending cellulose in a mixture which is a
non-solvent for the cellulose at the temperature of the suspension
and contains a tertiary amine oxide and water with or without an
organic liquid which is miscible with the tertiary amine oxide and
is a non-solvent for cellulose until sufficient amine oxide is
absorbed by the cellulose for complete dissolution of the cellulose
later on when it is heated. Preferably, the cellulose is steeped in
the amine oxide-water mixture or amine oxide-water-organic
non-solvent mixture for about 0.5 to about 30 minutes at a
temperature of about 85.degree. C. to 110.degree. C., until
sufficient amine oxide has been absorbed to provide from about
10-40% by weight cellulose and 75-85% amine oxide-water mixture in
the precursor after excess water or excess water and organic
non-solvent have been removed. The amine oxide-water absorbed by
the cellulose will contain from about 99 to about 70% by weight
amine oxide with the remainder being water.
The product of the invention may be used for making a shaped
cellulose product by heating the cellulose containing tertiary
amine oxide and water to a temperature where the cellulose
dissolves and removing the tertiary amine oxide while shaping the
solution.
The solid product produced by the process of the invention is
cellulose containing amine oxide and some water which, when heated,
will dissolve the cellulose. It has been found that by suspending
sheet or particulate cellulose in amine oxide and water, sufficient
amine oxide will be absorbed by the cellulose to dissolve the
cellulose upon heating to form a high solids solution having a
viscosity suitable for spinning. By controlling the temperature and
the proportions of the amine oxide-water or amine oxide-organic
non-solvent in the solution mixed with the cellulose, dissolution
of the cellulose in the solution can be postponed until it is to be
extruded or spun. Hence, the invention provides a method for making
a raw material which is complete in itself for the extrusion of
cellulose film and spinning of cellulose fibers and yarns.
The water and organic non-solvent mixed with the amine oxide
promotes swelling of the cellulose fibers thus facilitating
absorption of the amine oxide. This makes it possible to produce a
precursor which when heated is converted to a solution of higher
solids then the solutions disclosed in the above discussed prior
art. While water alone will cause swelling of the fibers, the
organic non-solvent assists in swelling the fibers and has the
advantage of providing a vehicle which assists in the removal of
excess water after the amine oxide has been absorbed.
Preferably, the mixture of amine oxide and water or amine
oxide-water-organic non-solvent is heated to a temperature of about
50.degree. to about 140.degree. C. before it is mixed with the
cellulose to promote uniform absorption of the liquid mixture by
the cellulose. The cellulose begins to swell shortly after it is
contacted by the amine oxide-non-solvent-water mixture. The
temperature of the slurry during the steeping or swelling step has
a significant effect on the extent to which the cellulose fibers
will become swollen. The optimum temperature to be used is the one
which will promote rapid and maximum swelling and a temperature at
which the tertiary amine oxide is liquid. The temperature must also
be below the boiling point of the organic non-solvent, if any, in
the mixture and below the decomposition temperature of the tertiary
amine oxide.
The organic non-solvent may be removed at any temperature at which
the cellulose does not dissolve. However, a temperature must be
maintained which permits efficient and rapid removal of the solvent
under vacuum. With most non-solvents the temperature may be from
about 40.degree. C. to about 90.degree. C. during non-solvent
removal. The non-solvent is removed under vacuum at a pressure of
as low as 0.01 mm of mercury.
As pointed out above, the product obtained by removal of the water
and/or organic non-solvent can be transferred immediately to
suitable equipment for shaping it into a regenerated cellulose
product if it is dry solid or it can be dried, cooled and stored
until some later date. If the product is soft and/or wet with amine
oxide, it may be dried at any suitable temperature at which the
cellulose will not dissolve.
The relative proportions of cellulose, water, amine oxide and
liquid organic non-solvent for cellulose which are mixed together
may be varied broadly depending upon the composition desired for
the product and as long as sufficient amine oxide-water mixture
will remain to dissolve the cellulose after the non-solvent has
been removed. Preferably, the ratio of liquid phase to cellulose in
the slurry should be such that the cellulose becomes saturated but
the excess of liquid phase is not so great that unnecessary
separation of large volumes of liquid is required.
The water content of the liquid mixture of amine oxide-water or
amine oxide-water-organic non-solvent mixed with the cellulose
should be as low as possible to avoid removing large volumes of
water at the end of the process. However, in the embodiment using
an organic non-solvent, the ratio of organic non-solvent and water
to cellulose must be such that the cellulose is swollen to promote
absorption of amine oxide by the cellulose. When the percentage by
weight cellulose in the product is to be low (say about 10%) the
ratio of non-solvent plus water to the cellulose at the beginning
of the process should be about 2.5 parts or more by weight
non-solvent plus water per part of cellulose. When the product
(cellulose containing amine oxide) is to contain a high percentage
of say about 40% by weight cellulose the ratio at the beginning of
the process should be more than about 0.25 part by weight
non-solvent-water mixture per part of cellulose and less than about
2 parts by weight non-solvent-water mixture per part of cellulose.
Since it is preferred that the product contain from 10 to 40% by
weight cellulose, a ratio of from 0.25 to 2.5 or more parts by
weight non-solvent-water mixture to cellulose is preferred.
The swelling of the cellulose appears to be independent of the
ratio of non-solvent to water. However, the ratio must be such that
the desired amine oxide-water ratio remains in the cellulose after
the non-solvent is removed. For best results, the amine oxide
should contain from about 10% to about 40% by weight water and the
amount of non-solvent in the slurry should be from about 15% by
weight to about 80% based on the weight of amine-oxide water in the
slurry.
Best results are obtained if the dried product after excess water
and/or organic non-solvent have been removed contains from about
10% to about 40% by weight cellulose, 0 to 20% by weight water and
about 90% to 50% by weight amine oxide.
The solid product after the organic non-solvent has been removed
and the water content has been reduced to from 0 to about 20% by
weight water based on the weight of the product may be heated to a
temperature of say 120.degree. C. or higher where the cellulose is
dissolved by the amine oxide-water mixture without the addition of
amine oxide, water or other material and the resulting solution may
be spun or otherwise shaped into a useful cellulosic product.
Any suitable cellulose may be used in the process such as, for
example, starch, cotton linters or various kinds of wood cellulose
but it preferred to use a rayon grade wood pulp.
Any suitable amine oxide which is a solvent for cellulose and is
compatible with water and, if an organic liquid non-solvent is
used, is also compatible with the organic liquid may be used such
as, for example, those disclosed in the aforesaid patents. However,
the preferred amine oxides are cyclic mono-(N-methyl-amine-N-oxide)
compounds such as, for example, N-methylmorpholine-N-oxide,
N-methylpiperidine-N-oxide, N-methylpyrollidone-oxide,
dimethylcyclohexylamine oxide, and the like.
Any suitable aprotic organic liquid non-solvent for cellulose which
will not react chemically with the amine oxide or cellulose may be
used such as, for example, an alcohol such as methyl alcohol,
n-propyl alcohol, isopropyl alcohol, butanol and the like, toluene,
xylene, dimethylsulfoxide, dimethylformamide, dimethyl acetamide or
the like.
In the following examples all parts and percentages are by weight
unless otherwise stated.
EXAMPLE I
About 40 grams of dry rayon grade wood pulp containing about 5.6%
water is soaked for about 60 minutes in N-methylmorpholine oxide
containing about 10% water. The wood pulp absorbs amine oxide and
water with swelling of the fibers. The wood pulp is removed from
the supernatant liquid and cooled at room temperature for about 30
minutes. The resulting product is a hard, breakable, hygroscopic
cellulose product containing about 26.9% cellulose, about 67.4%
N-methylmorpholine and about 5.2% water.
EXAMPLE II
About 200 grams dry wood pulp sheet is soaked in an excess of
N-methylmorpholine oxide containing about 12.4% water at about
85.degree.-90.degree. C. for about 15 minutes. The cellulose
absorbs liquid and swells. The cellulose-amine-oxide product after
cooling to room temperature is a hard, crystalline material
containing about 23.8% cellulose, about 64.4% N-methylmorpholine
and about 11.8% water.
EXAMPLE III
One sheet of wood pulp weighing about 40 grams containing 5.81%
water is soaked in an excess of N-methylmorpholine oxide containing
about 13.1% water at about 85.degree. C. for 5 minutes. The
cellulose absorbs liquid and swells becoming transparent. The
mixture is cooled for about 30 minutes to room temperature. The
product is a hard crystalline material which can be broken or
ground. It contains about 73.5% of the amine oxide, about 12.5%
water and about 13.5% cellulose.
EXAMPLE IV
About 320 grams wood pulp is soaked in about 1053 grams
N-methylmorpholine oxide containing about 13.9% for about 5 to 8
minutes at 78.degree. C. to 80.degree. C. until the liquid is
absorbed. The sheet is cooled and maintained at 25.degree. C. The
product is a hard crystalline material after 24 hours.
EXAMPLE V
About 2083 grams of N-methylmorpholine-oxide containing 37.1% water
are mixed in a round bottom flask or rotatable evaporator with
about 583 milliliters of toluene with stirring or rotation of the
evaporator. The mixture is heated to 80.degree. C. and about 500
grams of dry rayon grade wood pulp are mixed therewith and the
suspension is stirred about 10 minutes at atmospheric pressure. The
wood pulp absorbs amine oxide-water-toluene solution with swelling.
The temperature is reduced to about 60.degree. C. and the contents
of the vessel is placed under vacuum (about 27 inches mercury) to
strip the toluene and water from the vessel until substantially all
of the toluene has been removed and the water content of the
cellulose-amine oxide product is about 28.7%. The product is a soft
particulate cellulose containing absorbed amine oxide-water
mixture.
EXAMPLE VI
About 955 grams of N-methylmorpholine-oxide containing about 37.2%
water are mixed in an evaporator with about 600 milliliters of
methyl alcohol with stirring and heating to about 60.degree. C.
About 200 grams dry wood pulp are added to the mixture and the
evaporator is rotated at about 40 r.p.m. for about 10 minutes. The
cellulose absorbs liquid and swells. Liquid phase is removed under
vacuum until all of the methanol is recovered. The
cellulose-amine-oxide product then contains about 13% water.
EXAMPLE VII
About 332 grams of N-methylmorpholine-oxide containing about 26.58%
water is heated to about 85.degree. C. and placed in a suitable
flask. About 400 milliliters toluene and about 200 grams bone dry
wood pulp are mixed with the amine oxide and stirred for about 10
minutes. The cellulose absorbs liquid and swells. The mixture is
cooled to about 80.degree. C. and the flask is evacuated until all
of the toluene is removed. The water content of the cellulose-amine
oxide after the toluene is removed is about 16.45%.
About 400 milliliters of toluene are added to the contents of the
flask at 80.degree. C. and evaporation under vacuum is repeated
until the toluene is removed. The water content of the
cellulose-amine oxide product is then about 13.0%.
EXAMPLE VIII
About 1600 grams of N-methylmorpholine oxide containing 25% water
and about 400 milliliters of toluene are mixed and heated to a
temperature of about 80.degree. C. in an evaporator. About 400
grams bone dry wood pulp are added and the evaporator is rotated
for about 10 minutes at about 40 r.p.m. A vacuum is applied to the
product in a flask to reduce the pressure to about 26.5 inches of
Hg for about 25 minutes with removal of the toluene. The mean water
content of the amine-oxide saturated cellulose is about 13.7%.
EXAMPLE IX
About 952 grams of N-methylmorpholine-oxide containing 37% water
are mixed with about 200 milliliters isopropyl alcohol (IPA) and
the mixture is heated to 80.degree. C. in a rotary evaporator.
About 200 grams of wood pulp dried to a moisture content of about
6% are added to the amine oxide-water-IPA solution and the mixture
is heated to about 80.degree. C. for about 10 minutes while the
evaporator is rotating. An additional 400 milliliters of IPA are
added to the contents of the evaporator at 80.degree. C. and a
vacuum is applied to reduce the pressure to 27 inches Hg until the
IPA is removed and no more water is being removed. The cellulose
containing amine oxide-water is placed in a vacuum oven at
50.degree. C. and at 27 inches Hg for 4 days. Upon cooling after
removal from the oven, the cellulosic product hardens and is cut
into chips of about 3 cubic millimeters.
EXAMPLE X
The procedure of Example IX is repeated except that about 800 grams
of N-methylmorpholine oxide containing about 25% water, about 200
grams wood pulp and two 400 millimeter volumes of isopropyl alcohol
are used.
EXAMPLE XI
About 1070 grams of N-methylmorpholine-oxide containing about
25.27% water are mixed with about 200 milliliters of isopropyl
alcohol and heated to 80.degree. C. About 200 grams wood pulp are
added to the resulting mixture and the resulting suspension is
steeped until the wood pulp swells. About 400 milliliters of
isopropyl alcohol are added and after 10 minutes the isopropyl
alcohol and water are removed under facuum at 55.degree. C. and 27
inches Hg.
EXAMPLE XII
About 2175 grams of a solution which is about 49.4%
N-methylmorpholine-oxide, about 42.45% methyl alcohol and about
9.15% water (about 14.16% water based on the weight of the amine
oxide and water in the solution) is placed in an evaporator flask
and heated to about 80.degree. C. About 300 grams wood pulp chips
having an average particle dimension of about 1 sq. centimeter are
added to the solution. Liquid is removed under vacuum from the
mixture until all of the methyl alcohol has been removed. At this
point the water content is about 12.7% by weight and the cellulose
has swollen.
After seven days' storage of the product in a vacuum over at
50.degree. C. the product is about 19.5% by weight cellulose and
about 14.7% water. After three additional days' storage at ambient
temperature, the product had become hard and crystalline.
EXAMPLE XIII
About 587 g. of dimethylethanol amine oxide-water mixture
containing about 14.86% by weight water is placed in a 22 liter
flask. About 41 g. water and about 500 ml (395 g.) methanol are
added to the flask and the contents of the flask are heated to
about 80.degree. C. The liquid in the flask is composed of about
500 g dimethylethanolamine oxide, about 128.5 g. water, and about
395 g. methanol. About 97.6 g. of V 68 wood pulp sheet is cut into
about 3/16 inch squares and added to the flask. The ratio in the
flask is about 5 parts by weight water and methanol mixture per
part of cellulose.
The slurry is rotated in a rotary evaporator for about 15 minutes
during which time the cellulose fibers become swollen. A vacuum is
applied to the flask to reduce the pressure to about 27 inches of
mercury and the slurry is cooled to about 65.degree. C. One hour
later, the methanol is removed by distillation to produce cellulose
chips impregnated with amine oxide. The chips contain about 16% by
weight water and are dried at about 65.degree. C. under vacuum at
28 inches mercury absolute for 68 hours. The chips are cooled to
room temperature and are a hard cellulose chip product containing
about 10% by weight water.
EXAMPLE XIV
67.5 g. cellulose pulp are added in a flask containing 383.46 g.
Dimethylcyclohexyl-amine-oxide monohydrate, 116.82 g. water and
49.7 g. metanaol. The contents of the flask are heated to about
60.degree. C. for 10 minutes during which time the cellulose fibers
absorb the liquid solution and become swollen. A vacuum is then
applied to the flask, at about a 23-25 inches of mercury, for about
60 minutes at 80.degree. C. to remove a large part of the
methanol.
The impregnated cellulose then is dried in a vacuum over at
60.degree. C. for 80 hours under an about 25" vacuum, to remove any
remaining methanol and excess water to produce a solid, dry
cellulose product impregnated with the amine oxide.
The dried chips are cooled to room temperature and are observed to
be a hard cellulose chips product containing, theoretically 7.7%
water and 2.9% methanol. A hundred gram sample of the dried chips
is added to a mixer at 90.degree.-95.degree. C. for 70 minutes to
completely mix and dissolve the cellulose in amine-oxide ready for
extrusion into film, filament or fibers of cellulose.
In each of the foregoing examples, the cellulose absorbs the amine
oxide without dissolving.
The amine oxide used in practicing the invention may be prepared by
oxidizing the amine as described in U.S. Pat. Nos. 3,333,000,
3,447,939 or other suitable process. For convenience the amine
oxide has been referred to herein as simply "amine oxide" but it is
to be understood that the amine oxide is always a tertiary amine
oxide.
Although the invention is described in detail for the purpose of
illustration, it is to be understood that such detail is solely for
that purpose and that variations can be made therein by those
skilled in the art without departing from the spirit and scope of
the invention except as it may be limited by the claims.
* * * * *